- CFA Exams
- CFA Level I Exam
- Study Session 3. Quantitative Methods (2)
- Reading 10. Sampling and Estimation
- Subject 6. Confidence Intervals for the Population Mean
CFA Practice Question
A confidence interval was used to estimate the proportion of American new car owners who purchased domestic cars. A random sample of 58 new car owners generated the following 90% confidence interval: 0.376, 0.426.
Based on the interval given, does the mean population proportion of new car owners who purchased domestic cars exceed 39%?
A. Yes. The researcher has 90% confidence in the result.
B. The researcher cannot conclude that the mean exceeds 39% at the 90% confidence level.
C. No. The researcher has 90% confidence in the result.
User Contributed Comments 7
| User | Comment |
|---|---|
| danlan | m=0.401, the researcher knows the mean exceeds 37.6% at the 90% confidence level. |
| iceluke | he is just sure that the value is in between with 90%, but not that the mean is greater or not |
| joe3 | Good question! |
| octavianus | I think that it is important that the question refers to the "mean population" and not the mean SAMPLE. Maybe this explains why the researcher cannot make a conclusion. |
| sergashev | good one! |
| aakash1108 | nice! |
| clafuente | Hi, someone can help me explaining with more details please? Thanks so much |